From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:39849) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RLwLi-00089T-4R for qemu-devel@nongnu.org; Thu, 03 Nov 2011 08:24:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RLwLc-0006V8-6E for qemu-devel@nongnu.org; Thu, 03 Nov 2011 08:24:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54146) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RLwLb-0006Uz-Tc for qemu-devel@nongnu.org; Thu, 03 Nov 2011 08:24:44 -0400 Date: Thu, 3 Nov 2011 14:25:45 +0200 From: "Michael S. Tsirkin" Message-ID: <20111103122544.GH18296@redhat.com> References: <1320041218-30487-1-git-send-email-david@gibson.dropbear.id.au> <1320041218-30487-6-git-send-email-david@gibson.dropbear.id.au> <20111102071634.GA5613@redhat.com> <20111103051634.GQ5379@truffala.fritz.box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20111103051634.GQ5379@truffala.fritz.box> Subject: Re: [Qemu-devel] [PATCH 05/14] eepro100: Use PCI DMA stub functions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: anthony@codemonkey.ws, agraf@suse.de, rth@twiddle.net, joerg.roedel@amd.com, eduard.munteanu@linux360.ro, avi@redhat.com, qemu-devel@nongnu.org On Thu, Nov 03, 2011 at 04:16:34PM +1100, David Gibson wrote: > On Wed, Nov 02, 2011 at 09:16:34AM +0200, Michael S. Tsirkin wrote: > > On Mon, Oct 31, 2011 at 05:06:49PM +1100, David Gibson wrote: > > > From: Eduard - Gabriel Munteanu > [snip] > > > @@ -744,21 +713,26 @@ static void dump_statistics(EEPRO100State * s) > > > * values which really matter. > > > * Number of data should check configuration!!! > > > */ > > > - cpu_physical_memory_write(s->statsaddr, &s->statistics, s->stats_size); > > > - e100_stl_le_phys(s->statsaddr + 0, s->statistics.tx_good_frames); > > > - e100_stl_le_phys(s->statsaddr + 36, s->statistics.rx_good_frames); > > > - e100_stl_le_phys(s->statsaddr + 48, s->statistics.rx_resource_errors); > > > - e100_stl_le_phys(s->statsaddr + 60, s->statistics.rx_short_frame_errors); > > > + pci_dma_write(&s->dev, s->statsaddr, > > > + (uint8_t *) &s->statistics, s->stats_size); > > > + stl_le_pci_dma(&s->dev, s->statsaddr + 0, > > > + s->statistics.tx_good_frames); > > > + stl_le_pci_dma(&s->dev, s->statsaddr + 36, > > > + s->statistics.rx_good_frames); > > > + stl_le_pci_dma(&s->dev, s->statsaddr + 48, > > > + s->statistics.rx_resource_errors); > > > + stl_le_pci_dma(&s->dev, s->statsaddr + 60, > > > + s->statistics.rx_short_frame_errors); > > > > This might introduce a bug: stlXX APIs assume aligned addresses, > > an address in statsaddr is user-controlled so I'm not sure > > it's always aligned. > > > > Why isn't the patch simply replacing cpu_physical_memory_read > > with pci_XXX ? Any cleanups should be done separately. > > Because it seemed like a good idea at the time. When I first wrote > this, the possibility of unaligned addresses wasn't obvious to me. > So, I'm working on fixing this now. I can take one of two approaches: > > - Simply revert this part of the change, reinstate the e100_stl > functions as calling into dma_write(). > > - Alter the stX_dma() functions to work for unaligned addresses (by > falling back to dma_rw() in that case). This is a little more > involved but might make device writing safer in future. Yes but then we lose the atomicity guarantee. So this might still result in subtle emulation bugs. > Anthony, Michael, any preferred direction here? For 1.0 I'd go for option 1 as the simplest. > -- > David Gibson | I'll have my music baroque, and my code > david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ > | _way_ _around_! > http://www.ozlabs.org/~dgibson